The requirement is set out in FAR 61.56, and it generally states that:
...No person may act as pilot in command of an aircraft unless, since the beginning of the twenty-fourth calendar month before the month in which that pilot acts as pilot in command, that person has -
(1) accomplished a flight review given in an aircraft for which that pilot is rated by an authorized instructor; and
(2) a logbook endorsed from an authorized instructor who gave the review certifying that the person has satisfactorily completed the review.
The flight review usually takes place with an FAA-certified flight instructor in a session that must consist of a minimum of one hour of flight training and one hour of ground training. The training must include a review of the general operating and flight rules of FAR Part 91 and a review of maneuvers and procedures necessary to show that the pilot may safely exercise the privileges of the airman certificate held.
Beyond these specific requirements, the matter is left to the discretion of the person conducting the flight review. It is up to the reviewer whether the requirement for a flight review can be met in combination with other recent experience requirements, such as an instrument competency check. Any aircraft for which the pilot and the reviewer are rated is acceptable. And the two parts of the review do not necessarily have to be accomplished on the same day or by the same person. Therefore, you may accomplish the ground training requirement during an appropriate seminar, such as during AOPA Expo or at an AOPA Air Safety Foundation program, and accomplish the flight training portion on another day when you're out at the airport. However, both portions of the review need to fall within the preceding 24 calendar months of the month in which the flight is taking place, and both portions have to be logged.
Note that the regulation requires that the review must have been accomplished within the preceding 24 calendar months before the month in which the flight is taking place. Since the word calendar is used, the flight review does not have to be accomplished within the number of days it takes to add up to 24 months. Rather, the review requirement will have been met for two years following the last day of the month in which the pilot took the flight review.
There are a couple of exceptions to the need for a standard flight review. The flight review requirement can be met by passing and logging a checkride. Also, you can meet the flight review requirement by satisfactorily accomplishing one or more phases of an FAA-sponsored pilot proficiency award program, better known as the Wings program. Flight instructors can forego the one hour of ground training if they have satisfactorily completed a renewal of their flight instructor certificate. And glider pilots can substitute a minimum of three qualifying instructional flights in a glider for the one hour of flight training.
A flight simulator or flight training device may be used to meet the flight review requirements under certain conditions. The simulator or training device must be used in accordance with an approved course conducted by a Part 142 training center. Unless the simulator is approved for landings, the pilot must find another way to meet the three takeoffs and landings requirements within the preceding 90 days for carrying passengers. And, the flight simulator or flight training device must represent an aircraft or set of aircraft for which the pilot is rated.
Logging your flight review and all recent experience is important to meet the regulatory requirements for acting as pilot in command. It is always a good practice to make entries in your logbook right after the flight or training has taken place, especially if an endorsement from an instructor or examiner is necessary. Remember, the regulations require that the recent experience be logged prior to your acting as pilot in command.